MEXICO CITY - Hope mixed with fear Friday on a 60-foot stretch of a bike lane in downtown Mexico City, where families huddled under tarps and donated blankets, awaiting word of their loved ones trapped in the four-story-high pile of rubble behind them.

On Day 4 of the search for survivors of the 7.1-magnitude earthquake that brought down the seven-floor office building and many others, killing at least 293 people, hope rose and fell on the small things. A change in the weather, word that Japanese rescuers — strangers from half a world away — had joined the recovery effort, officials’ assurances that people remained alive inside, a call from a familiar number.

For Patricia Fernandez Romero, who spent the morning on a yellow folding stool under a handwritten list with the names of the 46 missing, it was remembering how badly her 27-year-old son, Ivan Colin Fernandez, sang and realizing how much she wanted to hear him again.

"There are moments when you feel like you’re breaking down," Fernandez said. "And there are moments when you’re a little calmer. ... They are all moments that you wouldn’t wish on anyone."

The families have been camped out since the quake hit Tuesday. More than half of the dead —155 — perished in the capital, while another 73 died in the state of Morelos, 45 in Puebla, 13 in Mexico State, six in Guerrero and one in Oaxaca.

Along the bike lane, where families slept in tents, accepting food and coffee from strangers, people have organized to present a united front to authorities, who they pressed ceaselessly for information about their loved ones.

They were told that water and food had been passed along to at least some of those trapped inside. On Friday morning, after hours of inactivity blamed on rain, rescuers were readying to re-enter the site, joined by teams from Japan and Israel. Fernandez said officials told them they knew where people were trapped on the fourth floor.

It’s the moments between those bits of information that torment the families.

"It’s that you get to a point when you’re so tense, when they don’t come out to give us information," she said. "It’s so infuriating."

Jose Gutierrez, a civil engineer attached to the rescue who has a relative trapped in the wreckage, gathered other families of the missing to let them know what was going on.

"My family is in there. I want them to get out," Gutierrez said, his voice breaking. "So ... we go onward."

A roller coaster of emotions played out on Friday for Roberta Villegas Miguel, who was awaiting word of her 37-year-old son, Paulino Estrada Villegas, an accountant who worked on the fourth floor and is married with two young daughters.

Wrapped in a fuzzy turquoise blanket against the morning chill she said that her daughter-in-law was contacted by a friend who said she had received a call from a cell number that belonged to her son, but there was no conversation. Her daughter-in-law ran to authorities with the information, but hours later returned to say that it was her husband’s old cell number. At first they held out hope that he had given his old phone’s SIM card to a co-worker who was using it to call out of the building. But eventually authorities traced the call to Queretaro state, extinguishing the latest glimmer of hope.

The arrival of rain late Thursday and the resulting work suspension drove Villegas’ optimism down. But Friday morning the arrival of the Japanese rescuers buoyed her once again.

Francisco Javier Mendez, whose daughter, Ana Laura, is also believed trapped inside the building, said his family had been told there were three points inside the collapsed structure where rescuers believe there are people, but only one where there are signs of life.

"They know because they have detected the warmth," he said. "What they don’t know is how many or how long they will last. Maybe six, they said."

Asked how it felt to know that perhaps there were only six survivors, the only word he could get out was "anguish."

Meanwhile, the time was nearing for bulldozers to be brought in to clear rubble and replace the delicate work of rescuers, though officials went to great pains to say it was still a rescue operation.

National Civil Defense chief Luis Felipe Puente acknowledged that backhoes and bulldozers were starting to clear away some wrecked buildings where no life has been detected or where teetering piles of rubble threatened to collapse on neighboring structures.

"It is false that we are demolishing structures where there could be survivors," Puente said. "The rescue operations will continue, and they won’t stop."

Back at the bike path, Cristal Estrada paced back and forth near the tent where she spent the night and worried about her missing brother, Martin Estrada, a 31-year-old accountant with a wife and three children, including a 4-month-old baby girl. She said she was frustrated not be able to personally help remove the rubble.

"They keep telling us there is life in there, but we keep on waiting," Estrada said. "There is life, yes, but we do not know if it is my brother’s."